1. Field of the Invention
The present invention relates generally to the field of pumps for moving liquids, and more specifically to a high volume pump for low viscosity liquids such as water as well as high viscosity liquids such as shampoo, mustard and ketchup, the pump including an outer cylindrical chamber having a central entrance port in a first end wall and a central exit port in a second end wall, a valve tube slidably contained within the cylindrical chamber and having cut out sections in a first edge nearest the chamber first end wall, a first cup member having an outwardly flared side wall with a lip resiliently bearing against the inner surface of the valve tube to create a seal near the valve tube first edge with the cut out sections beyond the side wall lip and a circular bottom wall with a diameter smaller than that of the first chamber end wall, the first cup member bottom wall being connected to spacer members extending from the first end wall, a plunger having a tubular stem containing a check valve plug and extending through the chamber exit port and having a second cup member attached to the tubular stem within the chamber also having an outwardly flared side wall bearing against the inner surface of the valve tube to create a seal and oriented to oppose the first cup member, so that when the plunger stem is slid out though the exit port, the first and second cup members move apart and create a low pressure area or vacuum between them, while the friction of the second cup member dragging against the valve tube pulls the valve tube a certain distance relative to the first cup member, and thus moves the valve tube first edge cut out sections beyond the first cup member side wall lip, breaking the seal and permitting liquid to be drawn by the vacuum through the chamber entrance port, around the first cup member side wall and through the cut out sections to enter the valve tube between the first and second cup members; and pushing the plunger stem back through the exit port causes the second cup member to once again drag against the valve tube and move the cut out sections back beyond the first cup member side wall lip, restoring the first cup member seal and pressurizing the liquid between the cup members, driving the liquid into a hole in the second cup member bottom wall and up through the plunger stem, dislodging the check valve plug in the stem and permitting the pressurized liquid to enter a nozzle and escape.
2. Description of the Prior Art
There have long been pumps for use in vessel lids for dispensing cleaning fluids, mustard, and other liquids. A problem with these pumps has been that they almost invariably contain floating ball type check valves. These check valves have proven unreliable, often sticking, jamming and blocking fluid delivery, or moving out of position and leaking when the pump is left resting on its side. Another problem with these ball check valves has been that they can greatly increase the expense of the pump.
It is thus an object of the present invention to provide a high velocity, high volume pump suited for use in vessel lids and tops, and which is reliable and does not include any ball check valves.
It is another object of the present invention to provide such a pump which seals against leakage at all times and in any orientation or position.
It is still another object of the present invention to provide such a pump which delivers liquid with minimal pump action, and does not require extensive priming.
It is finally an object of the present invention to provide such a pump which has a design well suited for easy and inexpensive molding and assembly.